Once again, this is supposed to be better than, and different from, "traditional" law! It has no purpose if the contracts don't actually do what they say. The whole point is that computers evaluate the contracts and do what they say.
I do think that calling blockchains "immutable" can be confusing to users not familiar with the concept and its nuances. And I personally hold no opinion on whether the currently locked up funds need to be returned to their owner with a fork. There is something to be said for both options, specifically in this case where there the "rightful owner" is clear (like the other cases mentioned in https://github.com/ethereum/EIPs/issues/156 ).